In the related art, a CCD (Charge Coupled Device) type or CMOS (Complementary Metal Oxide Semiconductor) type solid-state imaging device is mainly employed as an electronic device, such as a digital still camera, a camcorder, and a mobile information terminal, that takes an image of a photography subject. A number of such solid-state imaging devices are formed of a pixel array in which one million or more pixels are 2-dimensionally arranged, each pixel accumulates signal charges according to the light intensity from the photography subject, and an electrical signal according to the amount of accumulated charges is sampled and imaged as an analog or digital data.
However, generally, the solid-state imaging device has sensitivity in a specific electromagnetic wave wavelength band. For example, a solid-state imaging device based on silicon has sensitivity with respect to a wavelength shorter than that of a near-infrared ray (to 1.1 μm). However, the silicon-based solid-state imaging device has no energy resolution (wavelength resolution) with respect to electromagnetic waves, and it is difficult to specify a wavelength of detected light from the accumulated charges.
In a general color imaging device, 2-dimensionally arranged pixels are provided with various kinds of on-chip color filters allowing a specific wavelength component to selectively pass, to acquire a color image. A method of acquiring light intensity information of a plurality of wavelengths from a small number of adjacent pixel groups, and restoring the color image by an interpolation process based on demosaicing is employed.
In a general purpose camera, a Bayer method is common in which on-chip color filters of three primary colors of RGB are arranged in a houndstooth shape in units of 2×2 pixels. To raise sensitivity, a part of pixels may be provided with white pixels (pixels passing all visible wavelength bands), may be provided with complementary color filters of cyan, magenta, yellow, and the like, or may be provided with pixels detecting near-infrared rays.
Such filters may contain organic molecules such as pigments. However, the color filter formed of organic molecules has low wavelength resolution, it is difficult to perform optimization for a specific narrowband wavelength, and thus there is a limit in multi-color. A problem that transmission characteristics deteriorate due to interannual change caused by external stimuli, such as ultraviolet rays is pointed out (e.g., see Panasonic Technical Report, Vol. 54, No. 4, January 2009, p. 18 to 23).
Meanwhile, there is a solid-state imaging device acquiring delicate color information invisible to the naked eye. For example, in a special camera for medical use, science study, or and the like, it is insufficient to only coarsely separate visible wavelengths into three colors and to capture them, and it is necessary to capture seamless spectrum information with high wavelength resolution. To cope with such a usage, an imaging device having high wavelength resolution is proposed. For example, in a spectrum sensor using diffractive grating, it is possible to acquire color spectrum with very high wavelength resolution such as wavelength resolution (λ/Δλ) over 100, but the size of the device is large and thus it is limited to a special usage (e.g., see PASJ Vol. 54, No. 6, p. 819 to 832).
However, a hole array structure of periodically disposing holes having the same extent as a detection wavelength or more minute than that in a conductive thin film, or an island array structure which is in negative and positive relation with the same structure, is known as a plasmon resonator structure. The plasmon resonator structure which optimizes period of hole or island pitches, openings, dot shapes, and the like serves as a filter capable of adjusting a transmission wavelength by a physical structure (e.g., see Ebbesen, T. W. et al., Nature, Volume 391, Issue 6668, pp. 667 to 669, 1998, and P. B. Catrysse & B. A. Wandell, J.Opt.Soc.Am.A, Vol. 20, No. 12, p. 2293 to 2306, 2003).
For example, in JP-A-2008-177191 and International Publication No. 2008/082569 Pamphlet, a technique using the plasmon resonator structure as a color filter is disclosed.